COMPARISON - STLC and SDLC

In this chapter, we will understand the factors of comparison between STLC and SDLC. Let us consider the following points and thereby, compare STLC and SDLC.

STLC is part of SDLC. It can be said that STLC is a subset of the SDLC set.
STLC is limited to the testing phase where quality of software or product ensures. SDLC has vast and vital role in complete development of a software or product.
However, STLC is a very important phase of SDLC and the final product or the software cannot be released without passing through the STLC process.
STLC is also a part of the post-release/ update cycle, the maintenance phase of SDLC where known defects get fixed or a new functionality is added to the software.

The following table lists down the factors of comparison between SDLC and STLC based on their phases −

Phase	SDLC	STLC
Requirement Gathering	Business Analyst gathers requirements. Development team analyzes the requirements. After high level, the development team starts analyzing from the architecture and the design perspective.	Testing team reviews and analyzes the SRD document. Identifies the testing requirements - Scope, Verification and Validation key points. Reviews the requirements for logical and functional relationship among various modules. This helps in the identification of gaps at an early stage.
Design	The architecture of SDLC helps you develop a high-level and low-level design of the software based on the requirements. Business Analyst works on the mocker of UI design. Once the design is completed, it is signed off by the stakeholders.	In STLC, either the Test Architect or a Test Lead usually plan the test strategy. Identifies the testing points. Resource allocation and timelines are finalized here.
Development	Development team starts developing the software. Integrate with different systems. Once all integration is done, a ready to test software or product is provided.	Testing team writes the test scenarios to validate the quality of the product. Detailed test cases are written for all modules along with expected behaviour. The prerequisites and the entry and exit criteria of a test module are identified here.
Environment Set up	Development team sets up a test environment with developed product to validate.	The Test team confirms the environment set up based on the prerequisites. Performs smoke testing to make sure the environment is stable for the product to be tested.
Testing	The actual testing is carried out in this phase. It includes unit testing, integration testing, system testing, defect retesting, regression testing, etc. The Development team fixes the bug reported, if any and sends it back to the tester for retesting. UAT testing performs here after getting sign off from SIT testing.	System Integration testing starts based on the test cases. Defects reported, if any, get retested and fixed. Regression testing is performed here and the product is signed off once it meets the exit criteria.
Deployment/ Product Release	Once sign-off is received from various testing team, application is deployed in prod environment for real end users.	Smoke and sanity testing in production environment is completed here as soon as product is deployed. Test reports and matrix preparation are done by testing team to analyze the product.
Maintenance	It covers the post deployment supports, enhancement and updates, if any.	In this phase, the maintaining of test cases, regression suits and automation scripts take place based on the enhancement and updates.